Rear Differential Support Bracket SNAPPED: Pics Added

[LunarWolf]

It's only Aluminium.
Mine sheared into three pieces and yanked down the inner Offside CV joint, so it's a 10 day wait for delivery from germany for the two parts and a couple hours to refit.

But: Has anyone else any experience of this? Did you replace it with stock item or is there a Reinforced / upgraded part i don't know about?

Do you know why it sheared?

Any help / advice / thoughts / Nelson "HA-ha"s appreciated.
Well... maybe not the last one!

Thanks y'all!

[Shoppinit]

Have you been taking driving lessons from Mr Footlong?

[LunarWolf]

Luckily it wasn't me driving!
It was the local garage i use, so they are footing most of the bill!
I've had a good week! LoL

[Daveperc]

I would seriously question what the local garage was doing in the car to cause this to happen. To beak in the manner you describe it has to have been subject to one hell of a bang!

I have only ever done this to one car - my Escort Mexico years back. Long straight across a valley somewhere high up in Northumberland - it was dusk, and I didn't see that at the bottom of the valley there was a small hump-backed bridge. Hit it at over 90 and when we landed the rear suspension just fell to pieces! It had broken both ends of the top support bracket which mounted the shocks (Bilsteins naturally!). Driving was "interesting" for the next few hundred miles till I could get it fixed!

I reckon the mounting on the Beast is a LOT stronger - what the hell were they doing??

Dave

[LunarWolf]

Hi Daveperc...

I hear what you're saying...
But i do trust these guys (there's only two of them) implicitly....
I'd SAY i trust them with my life.... but that's not worth very much so i'll say i trust them with my RS6, which i've proved!!!

In their defence,
a) there was less than a mile on my odo' added from when i took it in.... and most of that was with me on a road test with me in the car!
b) i've known them for YEARS and have observational experience of their utmost respect for ANY cars. They work on Top end Bentleys to beaten up bangers, and they all get treated the same.
c) there's nowhere within 5 miles to rag the car like that! and i wouldn't believe they would, even given the chance. I know their short, long, slow and fast test routes.

Anyway:
being a cynic, there's always a doubt. and mine is merely 1%, so i cannot rule it out!

He said he was pulling out of the garage, onto the road, 2nd gear and accelerating. Straight line. Firm but not hard oand then heard a ban/crack and a rattle.stopped immediately, pulled over, and checked it out before towing back.

Bear in mind that i've only had the car for a short while and done less than 500 miles (with no drivetrain issues, admittedly).
I'm aware she HAS been driven hard hard in the past (tracked), (if you know the car you'll understand and know what i mean) so it could very well have been weakened at some point. Perhaps???

[Daveperc]

Fairy Nuff! I guess it could be accumulated fatigue cracking and they were just unlucky, but I don't think I've come across this failure in six and half years on here!

Probably not too much to fix.

Dave

[LunarWolf]

Hold that thought....
Here are some pics.
1) A picture of the underside of an amazing RS6... BamBam's not mine! (Thanks, Bam!)... with the Diff support bracket intactand in situ to demonstrate location for anyone interested who doesn't know. (there is a reason... and you'll see in my conclusion!



2) My (now) old bracket, off the car, sitting as it should...



3) and apart...



4) Ok... Here's the interesting bit.... This photo is the bracket flipped over, and of the "good" side...



5) And back to the snapped side, (reverse of) and there's a decidedly ominous notch present...



6) Another angle



7) And the last picture (sorry! LoL), another angle...



Right... so... at first glance, it really looked like it was an intentionally manufactured notch for a cable, pipe or suchlike. But it didn't make sense as there's nothing there!
A little closer look, and a swift rub, cleaning off a fair amount of road-crud, it was obvious that the notch was not intentional, but a chip broken off.
As you can see it created the weak point leading to the fracture.

I had a play around with an idea....
I held the unit on and over an axle stand, but to no avail.
A scissor jack: still nothing,
and then a (household) trolley jack and it SEEMED to sit quite flush.
I can therefore deduce (and i'm no expert, nor am i Sherlock Holmes!), that some fool tried to lift the entire rear end, by lifting from the centre of the vehicle, i.e the diff bracket!!!!!, and as it rolled to compensate the angular lift, it sheered the "notch" out, thus reducing the strength integrity of the unit, until the garage guys launched the car.

Would you agree? or have another theory?

[Shoppinit]

I like it. Seems plausible.

[Nobby]

Can't see the pics but I would agree that it sounds like you're correct.

Are you gonna ask the garage if they jacked it up at the back?

[Daveperc]

Seems entirely plausible.

I would guess the notch has been there some time creating a serious stress intensifier. I can't see in the photos, but does the broken surface change colour at some point - it will be darker nearer the notch. If so, then that would confirm that a stress fracture has been slowly growing until, by chance, it got to the point of breaking.

Good write up BTW

Dave

[mavada]

Watching the pic from bams car, was wondering if the right jackpoint havent damaged the fuel pump/filter...looks like they didnt use the recommended points to jack it up.

[subtacex]

To be quite honest,it looks as though something hit the support bracket taking a chunk out of it as opposed to a jack causing the initial damage leaving the remaining
material under stress causing the crack propagation

[ahoooga]

To be quite honest,it looks as though something hit the support bracket taking a chunk out of it as opposed to a jack causing the initial damage leaving the remaining
material under stress causing the crack propagation

+1 I was going to say maybe road debri has give it a pisser at some point in the past, although the jack theory is quite within reason as well.

[subtacex]

I would seriously think about changing the bushes for a flat profile polybush as I believe the e46 M3 had serious problems due to the same type

[bam_bam]

Watching the pic from bams car, was wondering if the right jackpoint havent damaged the fuel pump/filter...looks like they didnt use the recommended points to jack it up.

It's been mentioned before, resolution isn't great but I'd to think that MRC have lifted a fair few C5s.